1. Field of the Invention
The present invention relates generally to the field of improving the heat transfer resistance of a paneling system in which insulation material is confined between construction members, and more particularly, but not by way of limitation, to a paneling system providing improved insulating qualities to pre-engineered buildings and the like.
2. Discussion of the Prior Art
The pre-engineered building industry has developed into a multi-billion dollar segment of the building construction industry in the United States, and it has experienced an increasingly greater share of the construction industry budget throughout the world. The established method of erecting the roof or wall of a pre-engineered building is to erect the primary structural members; attach the secondary structural members to the primary structural members; secure the appropriate bracing members; roll blanket-type insulation across the secondary structural members; dispose panel members over the insulation; and connect the panel members and secondary structural members together by fasteners that penetrate the insulation. The securement of a panel member to a secondary structural member is performed by a workman who stands on top of the panel member and inserts fasteners through the panel member to attach it to the underlying secondary structural member.
The insulation of a pre-engineered building in the above described manner presents a major problem in the construction of such buildings. As the fasteners are installed through the panel members, the underlaying insulation is compressed between the panel members and the secondary structural members as the fasteners are attached to the secondary structural members. This is undesirable, as it reduces the thermal effectiveness of the insulation. Furthermore, the purpose of the fasteners is to secure the panel members and to transfer stress from the panel members, which is usually the exterior sheathing or roofing members, to the secondary structural members. This transferred stress may be tension, shear or compressive stress. As to the latter, compressive stress is created by downwardly directed live loads which are transferred through the insulation, which is generally a compressible but non-elastic material. As the panel members move relative to the secondary structural members during the life of the building, looseness occurs around the fasteners, and it is difficult, if not impossible, to maintain a water tight connection at the points where the fasteners penetrate the panel members.
One solution that has been offered to the problem of compressed insulation is the provision of a more elastic insulation board disposed between the insulation and the panel member. This insulation board is located such that the fasteners are caused to penetrate the insulation board before penetrating the insulation, and as the fasteners are attached to the underlaying secondary structural members, the insulation board spreads the compressive load of the fasteners over a larger area of the insulation and reduces the amount of compressive reduction of the thickness of the insulation. While this is an improvement over the previously described method, it still has a number of shortcomings. Among these is the fact that the insulation is still compressed under the insulation boards between the insulation board and the insulation. The insulation board is normally made of a soft material, and the compressive force caused by inserting the fasteners may tend to crush the insulation block. This in turn results in a number of detrimental features. These include dimpling of the single skin panel members, ponding of water in these dimples around the fastener heads and resulting excessive corrosion at these points. Continued working of the roof because of expansion and contraction can cause continued compression of the insulation board at the fastener points, and this can result in roof leaks between the heads of the fasteners and the panel members. This occurs because the pressure between the fastener heads and the panel members is no longer maintained, and even the provision of washer members will not guarantee a water tight seal.
Other problems with the use of the insulation boards include void spaces which are created between the panel members and the insulation at the edges of the insulation boards; these void spaces are detrimental from a heat transfer standpoint, and the installation of panel members with the insulation boards has been a problem from an erection standpoint. The insulation boards are relatively expensive and are difficult to install. Wind, which is often encountered, frequently dislodges the insulation boards before the overlaying panel members can be positioned, or the insulation boards are dislodged by the panel members as the panel members are being positioned.
The pre-engineered building industry has adopted the use of "diaphragm action" to resist wind loads on a building. Diaphragm action requires that force parallel to the plane of the roof panel be transferred through the fastening system to the underlaying secondary structural members. While the use of insulation boards has helped somewhat in regard to increasing the thermal effectiveness of the insulation, it remains that the diaphragm action on the panel members causes the stress to be transferred through the insulation, and the problem of maintaining water tight seals around the fasteners continues even with the use of such insulation boards, as such insulation boards do not entirely prevent initial and continuing compression of the insulation underlaying the panel members.
The patent issued to Taylor, U.S. Pat. No. 3,394,516, taught the use of a spacer between the panel members and the secondary structural members to prevent the panel members from being pulled so close to the secondary structural members as to crush or compress the insulation. The Taylor spacer has a plurality of pointed legs that served to penetrate the insulation, and sheet metal screws served to secure the panel members to the secondary structural members through the spacer. However, while the Taylor spacer substantially reduced the amount of compressive reduction of the insulation, the pointed legs of the Taylor spacer afforded a heat conducting bridge between the secondary structural members and the panel members. While the Taylor spacer does provide a mechanism for transferring the stress between the panel members and the supporting secondary structural members, the spacer legs of the Taylor spacer, being independent to the fasteners, could move to some degree relative to the secondary structural members, thus permitting some fretting of the fasteners with the panel members. This movement could eventually lead to a deterioration of both the water tightness of the fasteners and the thermal barrier as the insulation next to the pointed legs is spread about. Also, depending upon the type of seal provided with the insulation, penetration of the insulation by the Taylor spacer may in many instances prove difficult to effect without substantially compressing the insulation material while piercing the insulation seal, such as when a vinyl seal is provided. Finally, installation of the Taylor spacer required the placement of appropriately disposed holes in the secondary structural members for receiving the screw members which served to secure the spacer. To a workman located above the spacer, with the secondary structural members hidden from view by the insulation blanket, the only possible way to insert the screw members was to drill the holes from above the spacer and to insert the screw members in the holes while holding the spacer in the same location so as not to lose orientation with the newly drilled holes. This is often difficult to achieve on a windswept roof.